In various digital electronic systems, different signals may share a common bus. For example, an interrupt signal may appear on the bus in a microcomputer system, and various serial clocks may appear in a serial communication system. In the implementation of such digital systems, it may be important to know the source from which the signal is pulled active. This determination may also need to be made without interfering with the propagation of the signal on the bus line.
In the past, certain analog schemes have been implemented for detecting which signal source is originating the signal. But, use of an analog signal direction detecting circuit requires that the analog circuit be included in with the digital circuitry, which is likely to complicate manufacturing.
Certain digital schemes have been used in bus arbitration mechanisms to determine which of many users is requesting access to a bus, but without the ability to propagate the signal.
The art has lacked a simple digital circuit for both detecting which signal source is transmitting a digital signal onto a bus and propagating that signal on to another signal source device.